CHAPTER TOOLS

Keywords:

Magnetospheric substorms—Congresses

Summary

We compare geosynchronous particle signatures with aurora and geomagnetic disturbances during a substorm with multiple expansions, which began at 0852 UT on January 18, 1986. There were three localized expansions whose onset region moved successively westward. Energetic particle signatures observed from the geosynchronous satellite 1984–129 at the premidnight sector differed significantly for these three expansions in accordance with the transition of the onset region from the east to the west of the satellite foot-point. The results suggest that the source region of the energetic particle injection is confined within the local time sector of the expansion aurora. It was estimated that during this event an injection associated with an expansion started from a localized region with less than 28° in longitudinal width and was still confined within a region of about 40° even at the maximum of the expansion. This study also confirms that an injection boundary, if it ever exists, would be produced due to multiple localized injections, rather than due to a continuous expansion of a source region.